Harp seals spend most of their lives in the water, though some have been known to ride bits of drifting sea ice for short distances during migration. All harp seals must come up on land or ice to give birth, rear their young, and molt. From late February to March, seals relocate to the southern limit of their range to breed and give birth.

Pups are born on the short-lived seasonal platform of pack ice. Each female gives birth to only one pup; twins are extremely rare. Pups weigh 11 kg (24 pounds) at birth, but they lack the thick layer of blubber present in adults. Instead, they are insulated by their thick fur and obtain energy from their mothers’ milk, which is rich in fat. During their 12-day nursing period, pups gain about 2 kg (4.4 pounds) per day of blubber, which allows them to attain a weight of approximately 36 kg (79 pounds) at weaning. Weaning is abrupt as females stop nursing their young in order to mate with males. During this time, since the pups do not feed for up to six weeks, they may lose over 50 percent of their body mass. Eventually, hunger motivates the pups to enter the water and start feeding on their own.

Average-sized adults of both sexes measure 1.8 metres in length (6 feet). Male harp seals typically weigh 135 kg (300 pounds), females weigh 120 kg (265 pounds), and the largest adults may reach 180 kg (400 pounds). The face of an adult harp seal is completely black, while the gray coloration of its body is accented by a black harp-shaped marking on its back. Adults typically hold this coloration between five years of age and the end of their lives. The maximum life span for the harp seal is 35 years.

Adult seals mate either within the water or on top of ice floes. When fertilization occurs, the egg develops into a blastocyst, which floats freely within the uterus for four months until it implants itself in the uterine lining for active development. This delay in implantation stretches gestation time to 11.5 months and effectively postpones the birth of young to the period when enough pack ice is available to act as a whelping platform.

Harp seals are not strong divers compared with other seal species. Their maximum dive depth is 370 metres (1,200 feet), and they may stay underwater for only 16 minutes before resurfacing. Though they consume a wide variety of prey, their diet is centred on small fishes such as capelin (Mallotus villosus), Arctic cod (Boreogadus saida), or polar cod (Arctogadus glacialis). They also eat numerous invertebrates. Contrary to popular belief, harp seals rarely consume the commercially important Atlantic cod (Gadus morhua). Polar bears (Ursus maritimus), killer whales (Orcinus orca), and large sharks are the natural predators of harp seals.

Between the 1950s and ’70s, hunting pressure caused the world harp seal population to decline to around 1.5 million animals. About this time the killing of whitecoats began to generate worldwide public outrage, and in 1983 the European Union instituted a ban on seal products. These factors brought about a collapse in the market. In response, during the 1980s and early ’90s Canada’s Department of Fisheries and Oceans (DFO) set the annual “total allowable catch” (TAC) of harp seals at 186,000 animals—though the average number of harp seals killed by Canadian hunters each year during this time actually dropped to about 51,000, possibly because of the negative publicity and loss of markets. The smaller hunts occurring during this time allowed the harp seal population to recover.

As an outgrowth of this recovery and the Canadian government’s successful marketing of seal fur in the economically emerging countries of East Asia, the DFO increased the TAC to 240,000 in 1996. For the remainder of the decade, an average of about 270,000 seals was killed each year. In the early part of the 21st century, the DFO introduced a series of measures to expand the harvest further. In 2003 the first three-year plan was adopted, designed to allow the harvesting of 975,000 seals over three years but to forbid the taking of more than 350,000 in any given year. The new plans have been forced to adapt to changing conditions, however. For instance, in 2007, because of reductions in ice coverage in the Gulf of St. Lawrence and the coasts of Labrador and Newfoundland, the TAC was reduced to 270,000. The annual seal harvest remains an object of highly publicized controversy, attracting much international media coverage.

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